Reaction vessel



FIG. 1 is a top plan view of a reaction vessel showing my new design;

FIG. 2 is a left side view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a left end view thereof;

FIG. 6 is a right end view thereof.

The ornamental design for a reaction vessel, substantially as shown.